The Spaniard joined Chelsea instead and has gone on to score 41 times in 85 appearances for Arsenal's London rivals.

“I like Costa as a player,” Wenger said, prior to Arsenal's win over Chelsea on Saturday. “I like the qualities of the player. All the rest around is not needed. He’s a very strong player. He looks, since the start of the season, to have cleaned up his act, that he behaves more focused on the game. And that makes him more dangerous.

“I never thought he would leave Atlético Madrid at the time [he joined Chelsea], I was surprised. Would I have made a harder play for him had I known? Yes. I like him, as a quality striker.”

Arsenal wanted Gnabry to stay

Arsenal wanted to keep hold of Serge Gnabry in the summer and were close to extending his contract before the German opted to join Werder Bremen.